Add annotations to Trie.

Author: trekhleb

src/data-structures/trie/Trie.js

@@ -1,21 +1,33 @@
 import TrieNode from './TrieNode';
 
+// Character that we will use for trie tree root.
 const HEAD_CHARACTER = '*';
 
 export default class Trie {
   constructor() {
     this.head = new TrieNode(HEAD_CHARACTER);
   }
 
+  /**
+   * @param {string} word
+   * @return {Trie}
+   */
   addWord(word) {
     const characters = Array.from(word);
     let currentNode = this.head;
+
     for (let charIndex = 0; charIndex < characters.length; charIndex += 1) {
       const isComplete = charIndex === characters.length - 1;
       currentNode = currentNode.addChild(characters[charIndex], isComplete);
     }
+
+    return this;
   }
 
+  /**
+   * @param {string} word
+   * @return {string[]}
+   */
   suggestNextCharacters(word) {
     const lastCharacter = this.getLastCharacterNode(word);
 
@@ -26,17 +38,27 @@ export default class Trie {
     return lastCharacter.suggestChildren();
   }
 
+  /**
+   * @param {string} word
+   * @return {boolean}
+   */
   doesWordExist(word) {
     return !!this.getLastCharacterNode(word);
   }
 
+  /**
+   * @param {string} word
+   * @return {TrieNode}
+   */
   getLastCharacterNode(word) {
     const characters = Array.from(word);
     let currentNode = this.head;
+
     for (let charIndex = 0; charIndex < characters.length; charIndex += 1) {
       if (!currentNode.hasChild(characters[charIndex])) {
         return null;
       }
+
       currentNode = currentNode.getChild(characters[charIndex]);
     }
 

src/data-structures/trie/TrieNode.js

@@ -1,16 +1,29 @@
 import HashTable from '../hash-table/HashTable';
 
 export default class TrieNode {
+  /**
+   * @param {string} character
+   * @param {boolean} isCompleteWord
+   */
   constructor(character, isCompleteWord = false) {
     this.character = character;
     this.isCompleteWord = isCompleteWord;
     this.children = new HashTable();
   }
 
+  /**
+   * @param {string} character
+   * @return {TrieNode}
+   */
   getChild(character) {
     return this.children.get(character);
   }
 
+  /**
+   * @param {string} character
+   * @param {boolean} isCompleteWord
+   * @return {TrieNode}
+   */
   addChild(character, isCompleteWord = false) {
     if (!this.children.has(character)) {
       this.children.set(character, new TrieNode(character, isCompleteWord));
@@ -19,14 +32,24 @@ export default class TrieNode {
     return this.children.get(character);
   }
 
+  /**
+   * @param {string} character
+   * @return {boolean}
+   */
   hasChild(character) {
     return this.children.has(character);
   }
 
+  /**
+   * @return {string[]}
+   */
   suggestChildren() {
     return [...this.children.getKeys()];
   }
 
+  /**
+   * @return {string}
+   */
   toString() {
     let childrenAsString = this.suggestChildren().toString();
     childrenAsString = childrenAsString ? `:${childrenAsString}` : '';

src/data-structures/trie/__test__/TrieNode.test.js

@@ -25,6 +25,7 @@ describe('TrieNode', () => {
     trieNode.addChild('o');
 
     expect(trieNode.getChild('a').toString()).toBe('a');
+    expect(trieNode.getChild('a').character).toBe('a');
     expect(trieNode.getChild('o').toString()).toBe('o');
     expect(trieNode.getChild('b')).toBeUndefined();
   });